The invention relates to teaching aids of the kind comprising a frame, a plurality of elongate rods mounted horizontally in the frame and vertically spaced from each other and a plurality of number-bearing carriers supported on each rod. In a known aid, the carriers can be flipped between two different positions so as to present one or other of their two sides.
The present invention provides a teaching aid in which the number-bearing carriers are in the form of polyhedral blocks which can be selectively located in at least three discrete positions.
The invention provides a teaching aid comprising: a frame; a plurality of elongate rods mounted horizontally in the frame and spaced vertically from each other; and a plurality of polyhedral blocks rotatably mounted on each rod; wherein means are provided to releasably hold each polyhedral block in at least three discrete rotary positions on its respective rod.